JPH0839741A - Laminated film and capacitor using it - Google Patents

Abstract

PURPOSE:To improve running property and shaving resistance of a film at the time of manufacture of a capacitor and improve moisture resistance at the time of loading of voltage by layering a surface layer, wherein a relationship of a three-dimensional surface roughness and a glass transition temperature is specified, on a styrene polymer film having a syndiotactic structure. CONSTITUTION:On at least one face of a film consisting of a styrene polymer having a syndiotactic structure, a surface layer is layered. A relationship between three-dimensional surface roughnesses SRa(mum), Slambdaa(mum) and a glass transition temperature is made to be SRa>=0.01+0.02X(Tgc-Tgs)/Tgc. 3+4X(Tgc-Tgs)/Tgc<=Slambdaa<=20+10X(Tgc-Tgs)/Tgc. Here, Tgc represents a glass transition temperature of the syndiotactic polystyrene film layer and Tgs represents a glass transition temperature of the surface layer. A laminated film satisfies this relationship.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film and a capacitor using the same, and more specifically, it is suitable as a dielectric film for a capacitor, and is suitable for running the film at the time of manufacturing the film or the capacitor.
The present invention relates to a syndiotactic polystyrene-based laminated film and a capacitor which have excellent abrasion resistance, and have improved moisture resistance under voltage application and self-healing.

[0002]

2. Description of the Related Art A biaxially stretched film obtained by biaxially stretching and heat-fixing a resin composition containing a syndiotactic polystyrene-based polymer as a main component has excellent heat resistance and electric characteristics and is therefore developed as a dielectric for capacitors. (Japanese Patent Laid-Open No. 2-143851,
JP-A-3-124750 and JP-A-5-200858). Further, a capacitor having improved slipperiness in order to improve running performance and yield during manufacturing is known (JP-A-6-29146 and JP-A-6-29146).
80793).

[0003]

However, in these conventional syndiotactic polystyrene films,
Although abrasion resistance and running property were improved during the production of the film and during the production of the capacitor, the moisture resistance and self-healing property of the obtained capacitor under voltage load were not always satisfactory.

[0004]

Means for Solving the Problems The present invention has a surface layer laminated on at least one side of a film made of a styrene polymer having a syndiotactic structure, and the three-dimensional surface roughness SRa (μm) and The relationship between S λa (μm) and glass transition temperature is SRa ≧ 0.01 + 0.02 × (Tgc-Tgs) / Tgc 3 + 4 × (Tgc-Tgs) / Tgc ≦ S λa ≦ 20 + 10 × (Tgc-Tgs)
/ Tgc where Tgc is a glass transition temperature of the syndiotactic polystyrene film layer and Tgs is a laminated film characterized by satisfying the glass transition temperature of the surface layer. Further, the glass transition temperature of the surface layer is 90 ° C. or lower, the ratio of oxygen atoms to carbon atoms of the polar surface of the surface layer evaluated by X-ray photoelectron spectroscopy is 10% or more, and the surface layer Is 30% or less of the thickness of the laminated film, and the dielectric loss tangent (25 ° C, 1kHz) of the laminated film is
With a content of 0.001 or less, it is suitable as a dielectric film for capacitors and suppresses slipping off of lubricant during film manufacturing and capacitor manufacturing, and has excellent running properties and improved moisture resistance and self-healing properties under voltage load. The syndiotactic polystyrene-based laminated film thus obtained can be obtained. Further, a capacitor characterized by using a metallized syndiotactic polystyrene-based laminated film in which a metal thin film layer is formed on at least one surface of such a syndiotactic polystyrene-based laminated film has excellent electrical characteristics, and at the time of voltage load. It has excellent moisture resistance and self-healing property.

The polystyrene-based polymer having stereoregular syndiotactic structure used in the present invention has a tacticity in which the side chain phenyl group or substituted phenyl group is quantified by a nuclear magnetic resonance method, which is a diad (constituent unit). 85% or more for 2) and 50 for pentad (5 units)
It is desirable that the structure has a syndiotactic structure of not less than%.

The polystyrene-based polymer includes polystyrene, poly (p-, m- or o-methylstyrene), poly (2,4-, 2,5-, 3,4- or 3,5-dimethylstyrene). ), Poly (alkylstyrene) such as poly (p-tert-butylstyrene), poly (p-, m- or o-chlorostyrene),
Poly (halogenated styrene) such as poly (p-, m- or o-bromostyrene), poly (p-, m- or o-fluorostyrene), poly (o-methyl-p-fluorostyrene), poly ( p-, m- or o-chloromethylstyrene) and other poly (halogen-substituted alkylstyrenes), poly (p-, m- or o-methoxystyrene), poly (p-, m- or o-ethoxystyrene), etc. Poly (alkoxystyrene), poly (p-, m-
Or poly (carboxyalkylstyrene) such as o-carboxymethylstyrene), poly (alkyletherstyrene) such as poly (p-vinylbenzylpropylether), poly (alkylsilylstyrene) such as poly (p-trimethylsilylstyrene), Examples include poly (vinylbenzyldimethoxyphosphide) and the like.

In the present invention, among the polystyrene polymers, polystyrene is particularly preferred. Also,
The polystyrene polymer having a syndiotactic structure used in the present invention is not necessarily a single compound, and if the syndiotacticity is within the above range, a polystyrene polymer having an atactic structure or an isotactic structure is used. It may be a mixture of, a copolymer and a mixture thereof.

The polystyrene-based polymer used in the present invention has a weight average molecular weight of 10,000 or more, more preferably 50,000 or more.
00 or more. If the weight average molecular weight is less than 10,000, it is not possible to obtain a film having excellent strength and elongation characteristics and heat resistance. The upper limit of the weight average molecular weight is not particularly limited, but if it is 1500,000 or more, breakage occurs due to an increase in stretching tension, which is not preferable.

Further, the syndiotactic polystyrene film of the present invention can be produced by a known method, for example, a sequential biaxial stretching method in which longitudinal stretching and transverse stretching are carried out in order, as well as lateral / longitudinal stretching.
A stretching method such as a longitudinal stretching method, a longitudinal / transverse / longitudinal stretching method, or a longitudinal / longitudinal / transverse stretching method can be adopted, and the stretching method is selected according to various characteristics such as required strength and dimensional stability. Further, heat setting treatment, vertical relaxation treatment, lateral relaxation treatment, etc. can be performed.

The syndiotactic polystyrene polymer used in the present invention may contain, if necessary, an appropriate amount of a known antioxidant, antistatic agent or the like. The blending amount is preferably 10% by weight or less based on 100% by weight of the syndiotactic polystyrene polymer. If it exceeds 10% by weight, breakage easily occurs during stretching, resulting in poor production stability.

As the method for forming the surface layer, the syndiotactic polystyrene polymer and the resin composition for forming the surface are bonded in a molten state inside the die or at the opening of the die, laminated, extruded from the die and rapidly cooled to obtain an amorphous sheet. A method of stretching after producing a syndiotactic polystyrene polymer is extruded from a die and rapidly cooled to obtain an amorphous sheet or a uniaxially stretched film obtained by coating a surface-forming resin composition on a film and then further stretching, Examples include a method in which individually stretched films are adhered and laminated.

The resin laminated on the syndiotactic polystyrene of the present invention includes polyolefin resins such as polyethylene, polypropylene and polybutene, polyethylene terephthalate, polyethylene isophthalate, polyethylene-2,6-terenaphthalate, polybutylene terephthalate and the like. Polyester polymer, nylon 6,
Examples thereof include polyamide polymers such as nylon 66, nylon 12, nylon 4, polyhexamethylene adipamide, polyphenylene oxide, polycarbonate, polyarylate, polyether sulfone, and polyphenylene sulfide. The resin may be a mixture, a copolymer or a mixture thereof.

Then, the three-dimensional surface roughness S λa and
SRa is adjusted by the film forming conditions, the protrusion forming agent, the lamination and the like. The type and amount of the protrusion-forming agent are not particularly limited as long as the three-dimensional surface roughness S λa, SRa falls within a predetermined range, but, for example, silica, titanium dioxide, talc, kaolinite, zeolite, etc. Examples include addition of metal oxides, salts of metals such as calcium carbonate, calcium phosphate and barium sulfate, particles of an organic polymer such as silicone resin and crosslinked polystyrene, and the like. These fine particles may be used alone or in combination of two or more, and the average particle size of the fine particles used is 0.01 μm or more and 2.0 μm or less, particularly 0.05 μm or more and 1.5 μm. The following is preferred, and the degree of variation in particle size (ratio between standard deviation and average particle size) is preferably 25% or less. The addition amount is preferably 0.005% by weight or more and 2.0% by weight or less, and particularly preferably 0.1% by weight or more and 1.0% by weight or less, based on 100% by weight of the syndiotactic polystyrene polymer.

The three-dimensional surface roughness S λa of the surface layer of the syndiotactic polystyrene-based laminated film of the present invention and
SRa has an optimum range for suppressing slipping off of lubricant during film running and capacitor production, which depends on the glass transition temperature of the laminated film, and it has to be within the following range. I knew it was. SRa ≥0.01 + 0.02 x (Tgc-Tgs) / Tgc 3 + 4 x (Tgc-Tgs) / Tgc ≤S λa ≤20 + 10 x (Tgc-Tgs)
When / Tgc SRa is out of this range, the running property becomes poor, and defects such as wrinkles and scratches occur due to contact with rolls during film production and during capacitor production, which is not preferable.
Further, when S λa is less than 3 + 4 × (Tgc−Tgs) / Tgc, the running property becomes poor. Furthermore, S λa is 20 + 10 × (T
When it is larger than gc-Tgs) / Tgc, it is not preferable because white powder is generated due to the scraping of the protrusions, resulting in poor wear resistance.

In the present invention, the glass transition temperature of the surface layer is
It is preferably 90 ° C or lower. If it is higher than 90 ° C, the self-healing property tends to be poor. Further, the ratio of oxygen atoms to carbon atoms on the extremely thin surface layer of the present invention evaluated by X-ray photoelectron spectroscopy is preferably 10% or more. More preferably, it is 15% or more. When the ratio of oxygen atoms to carbon atoms on the extreme surface of the surface layer is smaller than 10%, the moisture resistance and self-healing property under voltage load become poor, which is not preferable. Here, when the ratio of oxygen atoms to carbon atoms on the extreme surface of the surface layer is 10% or more, the self-healing property is good even when the humidity resistance under voltage load and the glass transition temperature are 90 ° C or more. A laminated film is obtained. As a method of increasing the ratio of oxygen atoms to carbon atoms on the outermost surface of the surface to 10% or more, a surface layer (of course, the outer surface) is formed from a resin composition in which the ratio of oxygen atoms to carbon atoms is 10% or more. And a method of performing surface treatment by an oxidation method when the ratio of oxygen atoms to carbon atoms on the extreme surface of the surface layer formed of the resin composition is 10% or less. The thickness of the surface layer is 30% of the thickness of the laminated film
The following is preferred. If the thickness is more than 30%, the electrical properties such as capacitance and temperature of dielectric loss tangent, frequency characteristics, and heat resistance become poor, which is not preferable. The lower limit of the thickness is not particularly limited, but if the thickness is less than 0.005 μm, it is difficult to obtain the effect of improving the self-healing property, which is not preferable.

Further, in the present invention, the dielectric loss tangent (25 ° C., 1 kHz) of a laminated film in which a surface layer is laminated on at least one side of a film made of a styrene polymer having a syndiotactic structure is 0.001 or less. Is preferred.
When the dielectric loss tangent (25 ° C, 1kHz) is greater than 0.001, the good electrical properties of the film made of syndiotactic polystyrene polymer are affected by the properties of the resin of the laminated surface layers. However, it is not preferable because it will be damaged.

Further, in the present invention, a capacitor using a metallized syndiotactic polystyrene-based laminated film in which a metal thin film layer is formed on at least one surface of these laminated films, the slipping off of lubricant in the capacitor manufacturing process is suppressed, In addition, since the running property is excellent, variations in the characteristics of the obtained capacitor are reduced and the yield is improved. Moreover, the obtained capacitor has improved moisture resistance and self-healing property under voltage load.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation method of the film is shown below.

(1) Three-dimensional surface roughness S λa, SRa The surface of the film was measured using a stylus-type three-dimensional surface roughness meter (SE-3AK, Kosaka Laboratory Ltd.) with a needle radius of 2 μm and a load.
Cutoff value of 0 in the longitudinal direction of the film under the condition of 30 mg.
25 mm, measuring length 1 mm, 2 μm pitch
It is divided into 500 points and the height of each point is calculated by 3D roughness analyzer (SP
A-11). The same operation was continuously performed 150 times in the width direction of the film at intervals of 2 μm, that is, over 0.3 mm in the width direction of the film, and the data was taken into the analyzer. Next, S λa and SRa were determined using an analyzer.

(2) Glass transition temperature Using THERMOFLEX DSC-8230 manufactured by Rigaku Denki Co., Ltd.
The temperature rising rate was 20 ° C./min, and the sample weight was 5 mg.

(3) Oxygen atom-to-carbon atom ratio (O / C ratio) on the extreme surface by X-ray photoelectron spectroscopy The oxygen atom-to-carbon atom ratio was determined by the Shimadzu Corporation ESCA-850 as Mg source. The ratio of carbon atoms and oxygen atoms existing on the pole surface was measured using -Kα ray (1254ev). O / C ratio (%) = oxygen atomic weight / carbon atomic weight ×
100

(4) Dielectric loss tangent Yokogawa / Hewlett Packard Co. 4192A LF
Using IMPEDANCE ANALYZER, the dielectric loss tangent at 25 ° C and 1kHz was evaluated.

(5) Running and Scratch Resistance of Film The film is formed into a tape having a narrow slit, and the tape is rubbed on a metal guide roll to run at a high speed for a long time. The magnitude of the tension and the amount of white powder generated on the surface of the guide roll were evaluated and ranked on a scale of 5 as shown below. (A) Runnability 1st class; high tension (very many scratches) 2nd class; slightly high tension (many scratches) 3rd class; medium tension (slightly scratches) 4th class; tension slightly small (almost no scratches) 5th class; Low tension (no scratches) (b) Scratch resistance 1st class: White powder is very much generated 2nd class: White powder is often generated 3rd class: White powder is slightly generated 4th class: White powder is almost not generated 5 Grade: No white powder

(6) Humidity resistance under voltage load A capacitor of 100 V (DC) voltage is applied in an atmosphere of 60 ° C. and 95% RH and aged for 1000 hours to determine the rate of change in capacitance by Yokogawa / Hewlett-Packard. Co., Ltd. 4192A LF
It measured using IMPEDANCE ANALYZER. This is ΔC /
It is shown in C (%), and the smaller the rate of change in capacitance, the better the moisture resistance. Here, C is the capacitance before aging, and ΔC is the value obtained by subtracting the capacitance after aging from the capacitance before aging. The judgment is 5 as shown below.
Graded and ranked. 1st grade; -20> ΔC / C 2nd grade; -10> ΔC / C ≧ −20 3rd grade; −5> ΔC / C ≧ −10 4th grade; 0> ΔC / C ≧ −5 5th grade; ΔC / C ≧ 0

(7) Self-healing property (SH property) A laminated film with 600 Å thickness of aluminum vapor-deposited on one side is cut into a square with a side of 1 cm, two sheets are stacked, and further sandwiched by a rubber plate with a side of 2 cm, 2 kg. Was applied. In this state, a voltage was applied to the vapor-deposited film to cause dielectric breakdown, and the presence or absence of self-healing property was evaluated with 20 samples. 1st grade: No self-healing ability 2nd grade: Almost no self-healing ability 3rd grade: May not have self-healing ability 4th grade: Almost self-healing ability 5th grade: All self-healing ability

(8) Temperature characteristics Yokogawa / Hewlett-Packard Co. 4192A LF
The IMPEDANCE ANALYZER was used to evaluate the dielectric loss tangent at 150 ° C and 1 kHz. The dielectric loss tangent was evaluated and ranked in 5 stages as shown below. 1st grade; 0.05 or more; 2nd grade; 0.01 to 0.05 3rd grade; 0.005 to 0.01 4th grade; 0.001 to 0.005 5th grade; less than 0.001

Examples 1 and 2 Comparative Example 1 (a) Preparation of aqueous polyester solution Bayronal MD1200 (manufactured by Toyobo Co., Ltd.) 20 parts by weight (solid content 25%) Water 36 parts by weight Isopropyl alcohol 36 parts by weight Benzyl alcohol 8 parts by weight

(B) Production of Laminated Film Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.0 μm, variation = 20%)
Polyethylene terephthalate containing 40% by weight (IV = 0.
62) A polymer chip containing 4.0 parts by weight of resin and a polymer chip containing no protrusion-forming agent in a ratio of 0.2 to 9.8
(Comparative Example 1), 0.5 to 9.5 (Example 1), 1 to 9 (Example 2), and then dried and melted at 300 ° C.
Extruded from T-die with 200 μm lip gap, 40 ℃
It adheres to the cooling roll of the
An amorphous sheet of μm was obtained. The amorphous sheet is first preheated to 100 ° C. by a roll and further heated by using four infrared heaters with a surface temperature of 700 ° C.
Stretched 2.0 times in the machine direction at 9 ° C and then 1.25 in the machine direction at 125 ° C.
It was stretched 8 times. The coating solution obtained in (a) above was applied to both surfaces of the uniaxially stretched film by a bar coating method. The film is then preheated to 120 ° C with a tenter and stretched in the transverse direction.
The film was stretched 2.0 times at 120 ° C, then 1.6 times transversely at 150 ° C, and then heat set at 260 ° C. The total thickness of the obtained laminated film is 4 μm, and the total thickness of the surface layers is 0.1 μm.
The coating film was uniform. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. Table 1 shows film and capacitor characteristics
Shown in

Comparative Example 2 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.0 μm, variation = 20%)
0.5 to 9.5 by weight ratio of the polymer chip added with 4.0 parts by weight of the polymer chip and the polymer chip not added with the protrusion forming agent.
Example 1 was repeated except that the mixture was mixed and used. 50 aluminum on the coated surface of the obtained film
A roll-type film capacitor was prototyped by vapor deposition. The film and capacitor characteristics are shown in Table 1.

Examples 3, 4 Comparative Example 3 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.0 μm, variation = 20%)
Was added to a polymer chip containing 4.0 parts by weight of a polymer chip and a polymer chip containing no protrusion-forming agent at a weight ratio of 1: 9, and polyethylene terephthalate (IV = 0.62) containing no protrusion-forming agent as a surface layer. ) Are fed to separate extruders, melted, joined in a T-die so that polyethylene terephthalate forms both surface layers, extruded from the T-die with a 200 μm lip gap, and chilled to a 40 ° C chill roll. Adhesion, cooling and solidification by the electrophotographic loading method gave an amorphous laminated sheet of 44 μm. Here, the total thickness of the surface layers was set to 5 μm (Example 3), 11 μm (Example 4), and 14 μm (Comparative Example 3). The amorphous sheet was first preheated to 100 ° C by a roll and the surface temperature 70
It is further heated by using four infrared heaters at 0 ℃ and stretched 2.0 times in the machine direction at a film temperature of 139 ℃.
It was stretched 1.8 times in the machine direction at 125 ° C. The coating solution obtained in (a) above was applied to both surfaces of the uniaxially stretched film by a bar coating method. Then, the film was preheated to 120 ° C with a tenter and stretched in the transverse direction at a stretching temperature of 120 ° C by 2.0 times, and further stretched to 150 ° C.
After stretching 1.6 times in the transverse direction at ℃, it was heat set at 260 ℃.
The total thickness of the obtained laminated film was 4 μm. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. Table 1 shows the film and capacitor characteristics.

Examples 5 and 6 Comparative Example 4 Syndiotactic polystyrene (weight average molecular weight 2500
00) 100 parts by weight of calcium carbonate fine particles as a protrusion-forming agent (average particle size = 1.0 μm, variation = 20%)
Polymer chip added with 4.0 parts by weight of the polymer chip, a polymer chip to which the protrusion-forming agent was not added at a ratio of 1 to 9 by weight, and polyethylene-2,6- Telenaphthalate (Example 5), polypropylene (Example 6), and polyphenylene sulfide (Comparative Example 4) were fed to separate extruders and melted so that polyethylene terephthalate formed both surface layers in the T die. Bonded, extruded from a T-die with a 200 μm lip gap, adhered to a 40 ° C. chill roll by electrostatic loading and solidified by cooling to obtain a 44 μm amorphous laminated sheet. Here, the total thickness of the surface layer is 1.0
It was set to be μm. The amorphous sheet is first preheated to 100 ° C. by a roll, and further heated by using four infrared heaters having a surface temperature of 700 ° C., and a film temperature of 139 ° C.
Was stretched 2.0 times in the machine direction and further stretched 1.8 times in the machine direction at 125 ° C. The coating solution obtained in (a) above was applied to both surfaces of the uniaxially stretched film by a bar coating method. The film is then preheated to 120 ° C in a tenter and stretched at a stretching temperature of 120
The film was stretched 2.0 times at ℃, further stretched 1.6 times at 150 ℃ in the transverse direction, and then heat set at 260 ℃. The total thickness of the obtained laminated film was 4 μm. Aluminum was vapor-deposited on the coated surface of the obtained film by 500 Å to fabricate a roll-type film capacitor. The film and capacitor characteristics are shown in Table 1.

[0032]

[Table 1] From the table, the films obtained in Examples 1 to 6 were excellent in the running property of the film during the production of the film and during the production of the capacitor, the abrasion resistance, and the moisture resistance under the voltage load and the self-healing property were improved. It was a syndiotactic polystyrene-based laminated film and a capacitor.

[0033]

As described above, according to the present invention, by adopting the constitution as set forth in the claims, the film has excellent running property and abrasion resistance at the time of manufacturing a film or a capacitor. And, a syndiotactic polystyrene-based laminated film and a capacitor having improved moisture resistance under voltage load and self-healing property are provided,
Therefore, the industrial value of the present invention is great.

Claims (6)

[Claims] 1. A surface layer is laminated on at least one side of a film made of a styrene polymer having a syndiotactic structure, and the surface layer has three-dimensional surface roughness SRa (μm) and S λa (μm) and a glass transition. The temperature relationship is SRa ≧ 0.01 + 0.02 × (Tgc-Tgs) / Tgc 3 + 4 × (Tgc-Tgs) / Tgc ≦ S λa ≦ 20 + 10 × (Tgc-Tgs)
/ Tgc where Tgc is the glass transition temperature of the syndiotactic polystyrene film layer, and Tgs is the laminated film characterized by satisfying the relationship of the glass transition temperature of the surface layer. 2. The laminated film according to claim 1, wherein the glass transition temperature of the surface layer is 90 ° C. or lower. 3. The laminated film according to claim 1, wherein the ratio of oxygen atoms to carbon atoms of the pole surface of the surface layer evaluated by X-ray photoelectron spectroscopy is 10% or more. 4. The thickness of the surface layer is 30% of the thickness of the laminated film.
The laminated film according to claim 1, wherein: 5. A dielectric loss tangent (25 ° C., 1 kHz) of a laminated film in which a surface layer is laminated on at least one side of a film made of a styrene-based polymer having a syndiotactic structure.
] 0.001 or less, The laminated film of Claim 1 characterized by the above-mentioned. 6. A capacitor comprising a metallized syndiotactic polystyrene-based laminated film having a metal thin film layer formed on at least one surface of the syndiotactic polystyrene-based laminated film according to claim 1.